One of the most important strokes in tennis is the second serve.

A weakness in this shot puts the player on the defensive right from the start of the point.

Most of the top pros excel in getting the second serve deep, with a high kick, preventing the other player to hit a winner or to advance on the court.

Practice your second serve spinning a good quantity of balls over a high fence, to force you to serve up.

After you accomplish a good percentage of balls clearing the fence, come back to the court and now practice from the normal service position by the baseline, but spinning the ball up, with a lot of rotation.

You'll see the ball first going up and then curving down, kicking up after the bounce. The more kick, the more difficult for your opponent to return.

Sampras' second serve, even on hard courts, has been measured to spin sometimes over 5,000 RPM.

Such a rotation makes the ball feel heavier to the returning player, and also kicks within his racquet, impairing the accuracy of the return.

As a result, even at the top pro level, the other player usually returns well inside the court, rather than going close to the lines, thus keeping the advantage of the server through the beginning stages of the point.

Toss the ball a bit behind you, bend your arm so that most effort goes to the triceps, rather than your rotator cuff, and hit up past the ball.

Keep the wrist bent as if you were watching the inside of your hand, the racket strings should almost feel like a hat when it goes across above your head, moving from left to right for a right hander.

Even though you are serving towards your right, the angle on the racket will make the ball go to the left of the direction of your follow-through.

With practice, you will be able to have more and more clearance over the net and still bring the ball down in the service area, usually with good depth.